Which of these numbers is composite? ${19,\ 63,\ 71,\ 79,\ 97}$
A composite number is a number that has more than two factors (including 1 and itself). 19, 71, 79, and 97 each have only two factors. The factors of 63 are 1, 3, 7, 9, 21, and 63. Thus, 63 is the composite number.